Exhaust fan



H. w. AslRE EXHAUST FAN Filed May 1l, 1923 2 Shea't-Sh'aet l 2%. ffm y -If W WAL@ Nov. l0, '1925 H. w. AslRE EXHAUST FAN Affl-11e@ May 11l 1923 2 shuts-sha1 2 y 1. @Z3/m11' @A1111 ,WM y YM y Patented vNov. 10,l 1925.

' UNITED STATES PATENT OFFICE.

HORACE W. ASIRE, OF DAYTON, OHIO, ASSIGNOR TO GENERAL MOTORS RESEARCH Y CORPORATION, F DAYTON. OHIO, A CORPORATION OF DELAWARE.

v EXHAUST FAN.

Application led May 11,

- Fans, of which the following is a full, clear,

and exact description.

This invention relates to lcentrifugal lfans and is especially useful for exhaust fans.

An object of this invention is to increase the capacity and efliciency ofthe fan and to reduce the noise of operation thereof,

Further objects and advantages of the present invention will be apparent from the following description reference being had to the accompanying drawings wherein preferred embodiments of the present in vention are clearly shown.

In the drawings: l

Fig. 1 is an elevation of the fan wheel from the inlet side, and shows the slightly curved impelling vanes in dotted lines.

Fig. 2 shows a section through the fan wheel, as well as its location and connections when used for drawing air through a draft tube :for cooling an `internal-combustion en gine..

Similar reference characters refer to ilar parts throughout the several views.

The fan wheel designated in its entirety by numeral 10, is composed of two sido plates -11 and12 which have a series of,l impelling vanes 13 rigidly attached thereto by any suitable means. The method of' at- Sim- . tachment illustrated inl Fig. 1, has been found very satisfactory. Each of the vanes 13 is provided with one or more projections or'lugs 14 on eachside which ,extend through corresponding slots in the side plates v11 and -12 and are riveted' overl on the outside to form a rigid construction. yThe vanes 13 may kbe straight or curvedl and set at any desired angle according to the characteristics for which the fan is designed.- The curvature and angle of the vanes v13 as illustrated in Fig. 1, has beenfound to give very good results for the urpose of exhausting air from'a draft tu e as shown in Fig. 2. It.

wasfdiscovered however, that the hissing or whistling noise from the .operation ofthe fan could be very greatly reduced simpl by providing the small holes 15 throng the side plates 11 and 12 to permit a small amount of air to enter laterally into the 1923. serial No, 638,402.

air stream between the` vanes 13. These holes 15 may beprovided in only one side plate or in both and may be ,variouslyi shaped and located as'desired, however, the best results have been obtained by providing narrowslots substantially as shown in Fig. 1 and located midway between the vanes 13.

The method of operation o'f these slots 1'5 l v is as follows: The passageway between two vanes 13 for-ms a pipe or nozzle 16 through which thc air rushes. The inner edge of the vanes 13, being sharp and probably not exactly streamlined. with the rushing air','sets up a sound wave which is reinforced by the pipe 16 after the manner ofthe pipes' of at If however, the'slotsl 15 are pipe organ. provided, a small amount of air rushes lat-g erally into the pipe 16 and so breaks upthe sound wave passing therethrough, thus'destroying the reinforcing effect of the pipe;

lIn the case of slots in the vanes 13, a small amount of air rushes from the high pressure side to the low pressure side yof the vane and so breaks up the sound wave in somewhat the same manner. be understood that this explanation is given merely as ay theory andv that ,the invention is not in any way to be bound by they correctness of this theory.l It has been'found to produce `practicalresults and theabove It is of course tov description will enable others skilled in they artto practice the inventionregardless. of the actual manner 1n which the invention operates. v

In order to further decrease the noise and increase the efficiency of the fana; flaring. vinlet cone 2() is provided which assists in Without the'cone 20 however side plate 11 and leave the side plate12,

which of course has the tendency to increase the exit velocity` adjacent the'plate 11 and` decrease it toa very small amountv adjacent the plate 12. Obviously this effect vwill decrease the eciencyin every wayand will increase the noise due to the higher maximum velocity ofthe air overa portion of the length of vanes 13. The cone 20 is prefbrackets 37 and 38.

,will reduce the maximum exit velocity.

The cone 20 is shown rigidly secured to the side plate 11 by means of the spacer tubes 22 and the bolts 23. The flaring hub cone 21 may be also secured in place by the same bolts 23, as shown. The side plate l2 n is flared out at the inlet to give an easy turn to the entering air and to overlap the inlet ring 31 of the draft tube 32 to reduce leakage. The fan hub 35 'is mounted upon the spindle 36 supported upon suitable' The wheel 10 is driven j by the belt 40, the pulley 41 made integralv with the fan wheel, andthe pulley 42on the engine crank shaft. y

While the forms of embodiment of the invention as herein disclosed, constitute preferred forms, it is to be understood that other forms might be adopted, -all'coming within the scope of the claimsfwhich follow.

What is claimed is as follows: l v 1. A centrifugal fan of the class described comprising a side plate; a driving pulley carried by said side plate; a second side plate spaced apart from said first mentioned plate and having an opening through which air may enter the fan; a series of impelling bladesarranged between said side plates; a delecting cone having an edge lying substantially in the lane of the opening aforesaid and adaptedpto dev'i'deftheairy enterin the fan into` two streams; a plurality .o g spacers arranged' betweeii-tthe outer edge of said defiecting cone and'first mentioned side plateand fastening bolts for securing said cone in'engageinent with said spacers and t without an outer casing and to discharge dito said first mentioned side plate. 4

2. :A centrifugal fan of the class described comprising a side plate; adriving pulley; a

conical hub extending from the axis of rotation of the fan, and the4 periphery of which contacts with said irst mentioned side plate; a-deflecting fcone spaced apartA from said hub; fastening bolts extending through said deflecting cone, said conical hub and said side plate forfasteningsaid members together; a: second side plate spaced apart from said first mentioned side plate and having an opening through which air enters the fan; and a'series ofimpelling vanes arranged between said side plates and extending outwardly from the periphery of said conical .comprising two side plates spaced apart from one another; a series of impelling vanes arranged between said sidev plates; a central openingprovided inone of said side 'plates; a driving pulley carried by one of said side plates; a conical hub; a deflectin cone arranged within the fan and spaced apartmyfrom vthe side plate aforesaid which carries y'said pulley; and fastening bolts for fastening said last mentioned side plate, said iub Vand said delecting cone together'. 4:'Apcentrifugal fan adapted to operate withoutfanouter casing and to discharge Adirectll into the surrounding atmosphere throng out its entire circumference, said fan comprising side plates spaced apart from one another; a series of impelling blades arranged between said side plates whereby a plurality of air passages are provided; an inlet opening in one of said side plates through which air enters the fan and a plurality of openings extending through one of said side plates and leading from the air passages aforesaid directly into the surrounding atmosphere.

5. A centrifugal fan adapted to operate without an outer casing and to discharge directly into the surrounding atmosphere throughout its entire circumference, said fan comprising side plates spaced apart 4from, one another; a seriesof impelling vanes arranged between said side plates whereby `a plurality of. air passages are provided;.an inlet opening in one of said side plates through which air enters the fan and openings provided'in both of said side plates and leading from the air passages aforesaid directly into the surrounding atmosphere.

6, `A centrifugal fan adapted to operate signature. 1 HORACE W. ASIRE.

rovided; an- 

